[FLINK-32136][python] Fix the issue that Pyflink gateway server launc…

…h fails when purelib != platlib

This closes apache#22802.

flink-python/pyflink/java_gateway.py

@@ -27,6 +27,8 @@
 
 from py4j.java_gateway import (java_import, logger, JavaGateway, GatewayParameters,
                                CallbackServerParameters)
+
+from pyflink.find_flink_home import _find_flink_home
 from pyflink.pyflink_gateway_server import launch_gateway_server_process
 from pyflink.util.exceptions import install_exception_handler, install_py4j_hooks
 
@@ -100,6 +102,8 @@ def launch_gateway():
         os.close(fd)
         os.unlink(conn_info_file)
 
+        _find_flink_home()
+
         env = dict(os.environ)
         env["_PYFLINK_CONN_INFO_PATH"] = conn_info_file